mirror of https://github.com/apache/druid.git
103 lines
4.4 KiB
Markdown
103 lines
4.4 KiB
Markdown
---
|
|
id: gce-extensions
|
|
title: "GCE Extensions"
|
|
---
|
|
|
|
<!--
|
|
~ Licensed to the Apache Software Foundation (ASF) under one
|
|
~ or more contributor license agreements. See the NOTICE file
|
|
~ distributed with this work for additional information
|
|
~ regarding copyright ownership. The ASF licenses this file
|
|
~ to you under the Apache License, Version 2.0 (the
|
|
~ "License"); you may not use this file except in compliance
|
|
~ with the License. You may obtain a copy of the License at
|
|
~
|
|
~ http://www.apache.org/licenses/LICENSE-2.0
|
|
~
|
|
~ Unless required by applicable law or agreed to in writing,
|
|
~ software distributed under the License is distributed on an
|
|
~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
|
|
~ KIND, either express or implied. See the License for the
|
|
~ specific language governing permissions and limitations
|
|
~ under the License.
|
|
-->
|
|
|
|
|
|
To use this Apache Druid extension, [include](../../configuration/extensions.md#loading-extensions) `gce-extensions` in the extensions load list.
|
|
|
|
At the moment, this extension enables only Druid to autoscale instances in GCE.
|
|
|
|
The extension manages the instances to be scaled up and down through the use of the [Managed Instance Groups](https://cloud.google.com/compute/docs/instance-groups/creating-groups-of-managed-instances#resize_managed_group)
|
|
of GCE (MIG from now on). This choice has been made to ease the configuration of the machines and simplify their
|
|
management.
|
|
|
|
For this reason, in order to use this extension, the user must have created
|
|
1. An instance template with the right machine type and image to bu used to run the MiddleManager
|
|
2. A MIG that has been configured to use the instance template created in the point above
|
|
|
|
Moreover, in order to be able to rescale the machines in the MIG, the Overlord must run with a service account
|
|
guaranteeing the following two scopes from the [Compute Engine API](https://developers.google.com/identity/protocols/googlescopes#computev1)
|
|
- `https://www.googleapis.com/auth/cloud-platform`
|
|
- `https://www.googleapis.com/auth/compute`
|
|
|
|
## Overlord Dynamic Configuration
|
|
|
|
The Overlord can dynamically change worker behavior.
|
|
|
|
The JSON object can be submitted to the Overlord via a POST request at:
|
|
|
|
```
|
|
http://<OVERLORD_IP>:<port>/druid/indexer/v1/worker
|
|
```
|
|
|
|
Optional Header Parameters for auditing the config change can also be specified.
|
|
|
|
|Header Param Name| Description | Default |
|
|
|----------|-------------|---------|
|
|
|`X-Druid-Author`| author making the config change|""|
|
|
|`X-Druid-Comment`| comment describing the change being done|""|
|
|
|
|
A sample worker config spec is shown below:
|
|
|
|
```json
|
|
{
|
|
"autoScaler": {
|
|
"envConfig" : {
|
|
"numInstances" : 1,
|
|
"projectId" : "super-project",
|
|
"zoneName" : "us-central-1",
|
|
"managedInstanceGroupName" : "druid-middlemanagers"
|
|
},
|
|
"maxNumWorkers" : 4,
|
|
"minNumWorkers" : 2,
|
|
"type" : "gce"
|
|
}
|
|
}
|
|
```
|
|
|
|
The configuration of the autoscaler is quite simple and it is made of two levels only.
|
|
|
|
The external level specifies the `type`—always `gce` in this case— and two numeric values,
|
|
the `maxNumWorkers` and `minNumWorkers` used to define the boundaries in between which the
|
|
number of instances must be at any time.
|
|
|
|
The internal level is the `envConfig` and it is used to specify
|
|
|
|
- The `numInstances` used to specify how many workers will be spawned at each
|
|
request to provision more workers. This is safe to be left to `1`
|
|
- The `projectId` used to specify the name of the project in which the MIG resides
|
|
- The `zoneName` used to identify in which zone of the worlds the MIG is
|
|
- The `managedInstanceGroupName` used to specify the MIG containing the instances created or
|
|
removed
|
|
|
|
Please refer to the Overlord Dynamic Configuration section in the main [documentation](../../configuration/index.md)
|
|
for parameters other than the ones specified here, such as `selectStrategy` etc.
|
|
|
|
## Known limitations
|
|
|
|
- The module internally uses the [ListManagedInstances](https://cloud.google.com/compute/docs/reference/rest/v1/instanceGroupManagers/listManagedInstances)
|
|
call from the API and, while the documentation of the API states that the call can be paged through using the
|
|
`pageToken` argument, the responses to such call do not provide any `nextPageToken` to set such parameter. This means
|
|
that the extension can operate safely with a maximum of 500 MiddleManagers instances at any time (the maximum number
|
|
of instances to be returned for each call).
|
|
|